Decks can be manufactured in lengths up to 12 metres. In general terms decks are more structurally efficient when in double span condition. There are however instances where short single span sheets are required:-

• Due to site limitation for access
• For spans over 6000mm

Extended end laps can be used to create a double span condition whilst keeping the deck length to a minimum.

The deck must be fixed in every trough to support structure, with stitching screws to every web at each lap end.

The RoofDek D159 deck indicated above requires 12 stitching screws in the webs at each lap end.

Extended laps may be utilised for perforated decks, provided it is made clear in the fixing specification that the fixings go through solid material. However the extended overlap would block the perforations, wholly or partially, which will reduce the acoustic absorption.